1. Field of the Invention
This invention relates to disk drive suspensions, and, more particularly, to such suspensions particularly adapted to use in miniature disk drives. Miniature disk drives use smaller suspension components such as shorter and less robust load beams and wireless flexures. These components, having less size and mass, exacerbate the longstanding problems of precisely welding the components without distorting them. Accordingly, there is a need to lower the welding (laser) energy inputs into the load beam and flexure assemblies during manufacture. In the present invention, the load beam rigid portion is modified in advance of welding to reduce the volume of metal to be melted at the weld site enabling the use of less energy to weld, producing less distortion, and a more precise part.
2. Description of the Related Art
Conventionally, a disk drive suspension is made to the length of 18 mm. In the trend toward miniaturization, 14.5 mm and 11 mm suspensions have been introduced. The suspension typically comprises a stainless steel load beam for structural stiffness, a wireless flexure to provide a head gimbal, and a mount plate, usually fabricated of aluminum for attaching the load beam to an actuator arm. Laser welding is used to join the several components by a series of spot welds. Laser spot welding thus is integral part of the making of suspensions. Such welding provides relatively accurate positioning and good weld strength. Distortions from welding, however, induced by heat stress and/or material flow while in the molten state, can be troublesome. In conventional size suspensions welder through careful monitoring of the welding process routinely minimizes the occurrence of distortions to meet specifications. The arrival of smaller form factor suspensions with their reduced mass, tendency to distort more under the usual working conditions, and more stringent specifications has made existing manufacturing techniques inadequate. Customers are Increasingly imposing stringent visual and dimensional criteria for the laser weld. To compound the issue, particularly in newer suspension designs, more and more laser spot welds are utilized. And, these laser welds are playing a more critical role structurally than ever before. The concrescence of these factors militates a more precise and consistent weld technique and welded product.
It is an object therefore to provide a novel design suspension especially adapted to miniature disk drives. It is a further object to provide a suspension having improved welds with less distortion through the application of less energy into the weld, and less metal flow. A further object is to provide a suspension comprising a flexure and load beam assembly in which the load beam is locally surface etched to have a recess at potential weld sites to decrease the volume of material to be heated and flowed and thus decrease the heat input needed to weld. A still further object is to further reduce material volume and open a heat pipe to the underlying flexure metal layer by adding a smaller diameter opening through the web of metal beyond the etched recess in the load beam. Yet another object is to provide in such a suspension further features including an absence of side rails for lower suspension profile, a grounding structure integrated into the load beam base portion, a single window to the tail connection pads through the insulative film layer, and a mount plate marked for correctly oriented installation.
These and other objects of the invention to become apparent hereinafter are realized in a disk drive suspension for smaller disk drives, the suspension comprising a load beam having a base portion adapted for attachment by a mounting plate to an actuator arm, a spring portion, and a weldable metal rigid portion having a first face and an oppositely directed second face, the second face being adapted for attachment of a flexure carrying a slider thereon, the flexure comprising a laminate of a weldable metal layer opposite the second face, an insulative plastic film layer and a plurality of conductive traces spaced from the metal layer by the film layer, the rigid portion first face defining at distributed locations a series of etched recesses that locally reduce the thickness of the rigid portion adjacent the metal layer to be weldable with less energy than the full thickness of the rigid portion, the rigid portion being laser-welded to the flexure metal layer at the recesses.
In a further embodiment, the invention provides a smaller disk drive suspension comprising a load beam having a base portion adapted for attachment by a mounting plate to an actuator arm, a spring portion, and a weldable metal rigid portion having a first face and an oppositely directed second face, the second face being adapted for attachment of a flexure carrying a slider thereon, the flexure comprising a laminate of a weldable metal layer opposite the second face, an insulative plastic film layer and a plurality of conductive traces spaced from the metal layer by the film layer, the rigid portion first face defining at distributed locations a series of etched recesses that locally reduce the thickness of the web between the bottom of the recess and the second face adjacent the metal layer to be weldable with less energy than the full thickness of the rigid portion, and including as well a through hole between the bottom of the recess and the second face to further reduce amount of rigid portion and further reduce the amount of energy need to effect a weld, the rigid portion being laser-welded to the flexure metal layer at the recesses.
In these and like embodiments, typically, there is further included a cover layer on the laminate covering the conductive traces, and a tail connection pad on the base portion, the tail connection pad having a grounding structure comprising a downwardly stepped aperture through the insulative layer and the conductive traces, and/or the cover layer having a single aperture through to all of the individual pads; there is a mount plate for mounting the load beam base portion to an actuator, the mount plate bearing orientation indicium for correct orientation on the base portion, the orientation indicium comprising a clipped corner on the mount plate, and the load beam rigid portion is free of edge rails, the recess has a diameter of about 0.008 inch, the web has a thickness of about 0.0015 inch, plus or minus 0.006 inch, and the through hole has a diameter between 25% and 75% of the recess diameter, such as 0.004 inch diameter in a 0.008 inch diameter recess.
In a highly preferred embodiment, the invention provides a disk drive suspension for smaller disk drives, the suspension comprising a load beam having a base portion adapted for attachment by a mounting plate to an actuator arm, a spring portion, a weldable metal rigid portion free of edge rails and having a first face and an oppositely directed second face, the second face being adapted for attachment of a flexure carrying a slider thereon, the flexure comprising a laminate of a weldable metal layer opposite the second face, an insulative plastic film layer, a plurality of conductive traces spaced from the metal layer by the film layer, and a plastic film cover layer atop the conductive traces, a tail connection pad on the base portion, the tail connection pad having a grounding structure comprising a downwardly stepped circular aperture through the cover layer, the insulative layer and the conductive traces, the tail connection pad comprising a plurality of individual pads, the cover layer having a single aperture through to all of the individual pads, a mount plate for mounting the load beam base portion to an actuator, the mount plate bearing orientation clipped corner indicium for correct orientation on the base portion, the rigid portion first face defining at distributed locations a series of etched recesses that locally reduce the thickness of the web between the bottom of the recess and the second face adjacent -the metal layer to be weldable with less energy and less distortion of the rigid portion and the metal layer than required to weld through the full thickness of the rigid portion, a through hole between the bottom of the recess and the second face to further reduce amount of rigid portion and further reduce the amount of energy need to effect a weld, the rigid portion being laser-welded to the flexure metal layer at the recesses.
In its method aspects, the invention provides a method of laser welding a load beam rigid portion to a wireless flexure having a metal layer, including defining in advance of welding a recess in the rigid portion away from the flexure metal layer to provide a reduced thickness web at the bottom of the recess, and laser welding the rigid portion and rigid portion together at the web, or alternatively, also forming a through hole in the web, and laser welding the rigid portion and rigid portion together at the web.